Well, thought it was unlikely to last. After firing up fine, my 20+ year idle switch mode power supply which I use for my cobbled together disk setup decided to give up the ghost last night. Replacing the obviously dead X1 cap doesn't seem to have worked though today sadly.
Anyone able to point me at a decent priced suitable replacement that can handle a couple of old full-height 5.25s? Cheap Chinese modern hard disk supply I have on hand isn't up to the job and boy does it make the mains sing.
Done a bit more research now. My drives pre-date the Dragon, they are Y-E data and Micropolis 80 track full heights (the Y-E one is double sided).
The only supply info I can find for them suggests that Micropolis drives from their full-height series would like 1.5A on the 12V line at worst, but 1A even when idle and 1A on the 5V at all times. Assuming similar for the Y-E drive, my first suggestion's underpowered on the 12v line by some way. Thanks for the pointer to the dubious product listing sorchard - always read the datasheet!